Pump for liquids or hydraulic motor



July 3, 1928.

W. J. RUSDELL PUMP FOR LIQUIDS OR HYDRAULIC MOTOR D iled Sept. 11, 1925 o Patented July 3, 1928.

PATENT OFFICE.-

WILLIAM JOSEPH .RUSDELL, or XVOL'VERHAMPTON, ENGLAND.

BUMP non memos HYDRAULIC MOTOR.

Application filed September 11, 1925, Serial no. 55,776, and in Great Britain October 3, 1924.

This invention relates to reciprocating pumps or hydraulic motors having two or more pistons, buckets, rams or'the like acting on the liquid in series and operated by cams, for instance apparatus of the kind described in British Patent No. 176,067.

The cams usually operate in one direction only,'to give the pumping or power stroke, the return motion being caused by springs.

The movement during the return stroke may be quite different from that of the power stroke and the return stroke may occupy a'difierent (usually shorter) time.

By the present invention the return stroke of each piston is caused partly bythe power stroke of the other piston or pistons and partly by another cam or'cams,'hereinatter called the return'cam, acting in coiijunc tion with the said power stroke. I

In the case of a pump having two pistons, by the use of a rocking'lever the outward motion of one piston acting on the one end A of the rocking'levei', will cause the other end B'of the rocking lever to move inwards, but since the outward motion during the power stroke is usually different from the inwardmotion during thejreturn stroke, the movement of end B will not correspond with the return 'motion of the second piston.

The mounting of the pivot of the lever to slide under action of'a spring for the pun pose of compensating this lack of correspondence, has been described in the said British Patent No. 176,067.

According to the present invention, the pivot of the rocking lever is moved together with the lever by the return ca-m so as to correct the difference in motion between the two pistons.

The return cam acting through rollers,

rods, levers or the like will give the corbe taken up automatically. The tension of the spring may be adjustable.

The throw of the return cam which causes't'he pivot'to'move may be less than the individual movements of the pistons since this cam' has only to correct the difference in movement between the power stroke of the one piston and the return stroke of the other.

In the case of three pistons, a convenient method of applying the invention is to arrange the pistons equidistant from each other but not necessarily parallel and by employing a'rocking plate or frame and locating the pivot to be acted upon by the return cam in the rocking plate atthe centre of a triangle formed by the'points of contact between the piston rods or their extensions and the rocking plate. A similar arrangement would be suitable in the case of more pistons.

'In coimnun-icatingthe motion oli'the return'camto the pivot'this motion may be thero'cking arms, but may be merely held in contact by the spring referred to.

The invention is illustrated'in the accompanying drawings in whichFig. 1 is a diagrammatic elevation of one form of mechanism suitable for the purpose in view. Fig.

2 is a transverse section on line 22 of Fig. 1; Fig. 3 is a view similar toFig. 1 but showing a modification; Fig. 4 is a transverse 'sectioiion'line 4& of Fig. 3; Fig. 5'

is a fragmentary view showing a further modification; Fig. 6 is a section through a casing containing the driving shaft and the mechanism of the invention; and Fig. '7 is a perspective diagrammatic view of a mechanismsuitable for a pump or motor having three pistons, the pump chambers being omitted for the sake of cleariiess.

In Figs. 16, a represents the driving'shaft and Z), c the buckets of a pump having chambers Z) and 0 communicating by way of a passage (7 operated as described in British Patent No. 176,067 by cams e, f on ice ' the shaft; the cams act on the bucket rods 9, h through rollers 2', 70. The lever Z is the rocking lever already referred to as described in British Patent No. 176,067; its pivot on is suitably guided to slide towards and away from the shaft a in response to the action of the cam n which operates on the" pivot through roller 0, rod p, spring 9 and link 7'. The rod 10 slides in a tubular guide p. (shown partly in section in Figures 1 and 3) extending throughthe passage (5'.

In Figs. 1 and 3 the ends of the lever Z carryrollers Z resting on the'ends of the bucket rods g, h respectively. In Fig. 5 the lever Z is pivoted at one end to the bucket .usually occupies a shorter time, pivot mmust move outwards and inwards in order that the rollers Z shall remain in contact with the ends of rods 9 and it. During the period of overlap the pivot m will have an outward velocity equal to that ofthe rods themselves.

Cam a may be so shaped that the rod p moves exactly to correspond with the motion of pivot m, in which case the spring 9 will not alter its lengthand it is usually desirable to shape the cam substantially in this manner. In'certain cases, however, it may be desirable so to shape the cam that the spring 9 alters its length so as to exert dif-' ferent pressures for different positions of the bucket. If the profile of cam n is very accurately formed, so that the motion of rod ,2) exactly corresponds with that required for pivot m to maintain the rollers Z in contact.

with the ends of rods g and h, it is possible to dispense fvvith spring 9, but it is usually desirable to retain this spring to allow for irregularities in manufacture and it is sometimes desirable to cause the spring to vary its length, as when it is desired to reduce the load on the cams. When a spring is used, it may be in the form of a compression spring instead of the tension spring shown; it is usually desirable to provide means for adjusting the length of the pring so as to vary I its tension Or compression. In any case the tension must be sufficient to keep all the roll ersand cams .in contact with the parts against which they work. Any wear which may occur may be automatically takenup' by a shortening of the spring.

Figs. 1 and 2 differ from Figs. 3 and 4 in the mode in which the movement caused by the cama is transmitted to the rod'p. In Figs. 1 and 2 the roller 0 is guided so that its axis moves in a straight line which is an extension of the axis of rod 39.. In Figs. 3

and 4 the roller 0 is pivoted on a rocking arm 8 centred at s and connected by pivot (Z with rod 72. The profile of the cam and its position relative to shaft a differ from those of the cam in Figs. 1 and 2, owing to the effect of the rocking arm 8, but the profile must be such as to give the required movement to rod 79.

Referring to Fig. (3, this shows a construction by which the shaft a, its several cams and the rocking lever Z can all be enclosed in a casing If through which the rods 9 and h extend. The pivot on is mounted in a block a which slides in a sleeve acontaining a compression spring a adjustable by a screw The sleeve is connected as shown with the rollero and itself slides in a sleeve t carried by the casing 25. The rollers Z are accommodated in slots in the enlargements g, h of the rods 9 and h which carry the rollers iand 70. i

Fig. 7 shows three buckets w, y, .2 on corresponding rods :13, 3 z, the ends of which support a plate w. A revolving shaft a carries a cam platev Z) on which rest the rollers 0' on the lower end of the rods :0, y, a. The centre of the cam plate is raised to form a cam a against the face of which rests a roller '0 carried by one arm of a bentlever o turning on a stationary pivot 0 and having its other-arm linked by rod 4)" to the cent-re of the plate 40.

Theinvention has been described in connection with rectilinearly moving pistons or buckets, but is applicable also to pistons having angular or curvilinear motion as described in U. S. Patent Nos 1,615,139 of January 18,1927. I i

The spring 9 shown in the drawings is an example of a resilient device; hydraulic or pneumaticpressure may be substituted for the spring.

It will be noted that all the reciprocating parts are kept either in compression or in tension so that no reversal-of stress occurs 1 in these parts and there is automatic ad ust-- rocate, rotating cam mechanism adapted to move each piston throughits stroke in one direction, a member actuated by each piston during its stroke in the said direction to move another piston through its return stroke and a cam acting on said member to impart to it a movement whereby the movement of each piston through its return stroke is assisted. V M 2. A pump for liquids or a motor operated by liquid under pressure, comprising a number of pump chambers connected in series, apiston in each chamber adapted to re ciprocate, rotating canrmechanism adapted to move each piston through its power stroke and to permit each pistonto perform its re turn stroke in a period shorter than that occupied by its power-stroke, a member acts uated by each piston during its power stroke to move another piston through its return stroke, and a cam actingon .said member to impart to it ,a movement whereby each piston is caused to perform its return stroke in a period shortercthan that occupied by the power stroke.

, 3. A pu-mplfor liquids or aniotor operated by a liquid under pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, rotating cam mechanism adapted to move each piston through-its power stroke, a pivoted member actuated by each. piston during its power stroke to move about itspivot and so to cause another piston to movethrough its return stroke, and a cam acting on said member at its pivot to impart to it during the power stroke of eachpiston a movement whereby the movement of a pistonthrough its return stroke is assisted.

4. A pump for liquids or a motor operated by a liquid under pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, a rotating cam actuating each piston to cause, it to. perform its power-stroke,

and having a. cam profile such that for a substantial portion of the power stroke of a piston, for small equalangu-lar movements of the cam, the piston ,is caused to move through equal longitudinal distances, and such that each piston is free to perform its return stroke in a period shorter than that occupied by its power stroke, a member actuated by each piston during-its power stroke to move another piston through its return stroke, and a rotating cam acting on said member to impart to it a movement whereby each piston is caused to perform its return stroke in a period shorter than that occupied by its powerstroke.

5. A pump for liquids or amotor operated by liquid under pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to recip-' rocate, piston rods carrying said pistons, rotating cam mechanism adapted to actuate each piston rod to move the piston carried thereby through its power stroke and to per mit each piston to perform its return stroke in a period shorter than that occupied by the power stroke, a member actuated by the piston rod of each piston during its power stroke to move another piston rod and the piston carried thereby through its return stroke, anda rotating cam acting on said member and having its profile of such shape that thepiston rod of each piston is maintained during its return stroke substantially in contact with the cam device by which it is caused to perform its power stroke.

6. A pump for liquids or a motor operated by liquid under pressure, con'iprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, piston rods carrying saidpis tons, rotating cam mechanism adapted to actuate each piston rod to move theipiston carried thereby through its power stroke, and to permit each piston ,to-perform its return stroke in a period shorte* than that occupied by the power stroke, a rocking device actuatedby the pistonrod of each piston during its power stroke to move another piston rod and the piston carried thereby through its return stroke, a member on which said rocking device is pivoted and a rotating cam imparting a reciprocating motion to .said member and, therefore, to the pivot of the rocking device, and having its profile of such shape that the rod of each piston is maintained during its return stroke sub stantially in contact with the cam device by which it is caused to perform its power stroke.

7. A pump for liquids or a motor operated by liquid umlerpressure comprising a num ber of pump chan'ibers connected in series, a piston in each chamber adapted to reciprocate, rotating cam mechanism adapted to move'each piston through its stroke in one direction, a member actuated by each piston during its stroke in the said direction to move another piston through its return stroke, a cam acting on said member'to impart to it av movement whereby the movement of each piston through its return stroke is assisted and a resilient device interposed between said member and said cam acting thereon.

8. A pump for liquids or motor operated by liquid under pressure, comprisin a munber of pump chambers connected in series, a piston in each chamber adapted to reciprocate, rotating cam mechanisn'i adapted to move each piston through its power stroke. and to permit each piston to perform its return stroke in a period shorter than that occupied by its power stroke, a member actuated by each piston during its power stroke to move another piston through its return stroke, a cam acting on said member to impart to it a movement, whereby each piston is caused to perform its return stroke in a period shorter than that occupied by the power stroke and a resilient device interposed between said member and said cam acting thereon.

9. A pump for liquids or a motor operated by a. liquid under pressure, comprising a number of pump chambers connected in loo series, a piston in each chamber adaptedto reciprocate, rotating cam mechanism adapted to move each piston through its power stroke, a pivoted member actuated by each piston during its power stroke to move about its pivot and so to cause another piston to move through its return stroke, acam acting on said member at its pivot to impart ated by a liquid underpressure, comprising I a number of pump chambers connected in V series, a piston in each chamber adapted to thereon.

reciprocate, a rotating camactuating each piston to cause it to perform its power stroke and havinga cam profile such that for a substantial portionof the-power stroke of a piston, for small equal angular move ments ofthe cam, the piston is caused to move through equal longitudinal distances and such that each piston is free to perform its return stroke in a period shorter than that occupied by its power stroke, a member'actuated by each piston during its power stroke to move another piston through its return stroke, a rotating cam acting on said member to impart to it a movement whereby each piston is caused to perform its return stroke in a period shorter than that occupied by its power stroke and a resilient device interposed between said member and 'saidcam acting thereon. r

11. A pump for liquids or a motor operated by liquid under pressure, comprising a number of pump chambers connected in series, a piston'in each chamber adapted to reciprocate, piston rods carrying said pistons, rotating cam mechanism adapted to actuate each piston rod to move the piston carried thereby through its power stroke and to permit each piston to perform its return stroke in a period-shorter than that occupied 1 by the power stroke, a member actuated by the piston 'rod of each piston during its power stroke to move another piston 'rod and the piston carried thereby tlnoughgits return stroke, a rotating cam acting on said member and having its profile of such shape that the piston rod of each I )iston is maintained durim its return stroke substantially-in contact with the cam device by which it is caused to perform its power stroke and a resilient device interposed between said memberand said cam acting 12. A pump for liquids or a motor operated by liquid under pressure comprising a number of pump chambers connectedin series, a piston in each chamber adapted to reciprocate, rotating cam mechanism adapted to move each piston through its stroke movement of each piston through its return stroke is assisted and a resilient device interposed between said member and said cam acting thereon and subjected to a stress which is in the same direction at all stages in the operation of the apparatus.

13. A pump for liquids or a motor operated by liquid under pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, rotating cam mechanism adapted to move each piston through its power stroke and to permit each piston to perform its return stroke ina period shorter than that occupied by its power stroke, a

member actuated by each piston during its 1 power stroke to move another piston through its return stroke, a cam acting on said member to impart to it a movement whereby each piston is caused to perform its return stroke in a period shorter than that occupied by the power stroke and a resilient device interposed between said member and said cam acting thereon and subjected to a stress which is in the same direction at all stages in the operation of the apparatus. 7 1

14. A pump for liquids or .a motor operated by a liquid under pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, rotating cam mechanism thereon and subjected to a'stress which is in the same direction at all stages in the operation'of the apparatus. 7

15. A pump for liquids or a motor operated" by liquid under pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, a rotating ca-m actuating each piston to cause it to perform its power stroke and having a cam'profile such that for a substantial portion of the power-stroke of a piston, for small equal angular movements of the cam, the piston is caused to move through equal longitudinal distances. and such that each piston is free to perform its return stroke in a period shorter than that occupied-by its power stroke, a member actuated by each piston during its power stroke to move another piston through its return stroke, a rotating cam acting on said member to impart to it movement whereby each piston is caused to" perform its return stroke in a period shorter than that occupied by its power stroke and a resilient de vice interposed between said member and said cam acting thereon, and subjected to a stress which is in the same direction at all tons, rotating cam mechanism adapted to actuate each piston rod: to move the piston carried thereby through its power stroke and to permit each piston to perform itsreturn stroke in aperiod shorterthan: that occupied by the power stroke, a member actuated by the piston rod of each piston during its powerstroke to move another piston rod and the piston carried thereby through its return stroke, arotatingcam acting on said memberand having its profile of such shape that the piston rod of each piston is maintained during its return stroke-substantially in-cont'a'ct with the cam device by which it is caused to perform its power stroke and a resilient device interposed between said member and said cam acting thereon, and subjected to a stress which is in the same directionat all stages in the operation of the apparatus.

17. A pump for liquids or a motor operated by liquid under pressure comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, rotating cam mechanism adapted to move each piston through its stroke in one direction, a member actuated by each piston during its stroke inthe'said'direction to move another piston through its return stroke, a cam acting on said member to impart to it a movement whereby the movement of each piston through its return stroke is assisted and a resilient device interposed between said member and said cam acting thereon and subjected to stress, and means for adjusting the resilient device with respect to the stress to which it is subjected.

18. A pump for liquids or a motor operated by liquid under pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, rotating cam mechanism adapted to move each piston through its power stroke and to permit each piston toperform its re turn stroke in a period shorter than that oc cupied by its power stroke, a member actuated by each piston during its power stroke another piston through its retu n 7. acting on said member to part to it a movement whereby each piston is caused to perform its return stroke in a period shorter than that occupied by the power stroke, a resilient device interposed betweensaid member and said cam acting.

thereon and subjected to stress, and means for adjusting the resilient device with-respect to the stress to which it is subjected.

19. A pump for liquids or a motouoperated by a liquid under pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to. reciprocate, rotating cam mechanism adapted to move each piston through its power stroke, a pivoted member actuated by each pistpn during its power stroke to move about 1ts plvot and so to cause another piston to move through its return stroke, a cam acting on said member at its pivot to impart toit during the power stroke ofeach piston a movement whereby the movement ofa piston through its return stroke'is assisted, a resilient device interposed between said member and said cam acting thereon and subjected to stress, and means for adjusting the resilient device with respect to the stress to which it is subjected.

20. A pump for liquids or a motor operated by a liquidunder pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, a rotating cam actuating each piston to cause'it to perform its power stroke, and having a cam profile such that for a substantial portion of the power stroke of a piston, for small equal angular movements of the mm the piston is caused to move through equal longitudinal distances, and such that each piston is free-to perform its return stroke in a period shorterthan that occupied by-its power stroke, a member actuated by each piston-during its power stroke to move another piston through its return stroke, a rotating canracting on said member to impart to it a movement whereby each piston 'is caused to perform its return stroke in a period shorteruthan that occupied by its power stroke, a resilient device interposed between said member and said cam: acting thereon and subjected to stress and means for-adjusting the resilient device with respect to the stress to'which it is subjected.

21. Apump for liquids or a motor operated by liquid under pressure, comprising a' number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, piston rods carrying said pistons, rotating cam mechanism adapted to actuate each piston rod to move the piston carriedthereby through its power stroke and to permit'each piston to perform its return stroke in a period shorter than that occupied by the power stroke, a member c u tee by th iston rod or each piston c-J i stroke to move another piston rod and the piston carried thereby through its return tained during its return stroke substantially w in contact with the cam device by which it is caused to perform its power stroke, a resilient device interposed between said member and said cam acting thereon and subjected to stress, and means for adjusting the resilient device with respect to the stress to'which it is subjected.

22. -A pump for liquids or a motor operatedvby liquidnnder pressure, comprising a -number'of pump chambers connected in series, a piston-m each chamber adapted to reciprocate, piston rods carrying said pistons, rotating cam mechanism adapted to actuate each piston rod to move the piston carried thereby through its power stroke, and to permit each piston to perform its return stroke in a period shorter than that occupied by the power stroke, a rocking device actuated by the piston rod of each piston during its power stroke to move another piston rod and the piston carried thereby through its return stroke, a member on which said rocking device is pivoted, a rtating cam imparting a reciprocating motion to said member and therefore to the pivot of the rocking device, and having its profile of such shape that the rod of each piston is maintained during its return stroke substantially in contact with the cam device by which it is caused to perform its power 7 stroke, and a resilient device forming a part of saidmember on which the rocking device is pivoted and situated intermediately of the rocking device and the cam actuating said member, so that the cainmust transmit motion to the rock ng device through'the said resilient device '23. A pump for liquids or a motor operated by-liquid under pressure, comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, piston rods carrying said pistons, rotating cam mechanism adapted to actuate each piston rod to move the piston carried thereby through its power stroke, and to permit each piston to perform its re: turn stroke in a period shorter than that occupied by the-power-stroke, a rocking deviceactuated by the piston rod of each piston during its power stroke to move another piston rod and the piston carried thereby I through its return stroke, a. member on which said rocking device is pivoted, a rotating cam imparting a reciprocating motion to said member and therefore to thepivot of the rocking device, and having its profile of i such shape that the rod of each piston is maintained during its return stroke substantially in contact with the cam device by which it is caused to perform its power stroke, and a resilient device forming a part of said member on which the rocking device is pivoted and situated intermediately of the rocking device and the c'amactuating said member, so that the cam must transmit mo tion to the rocking device through the said resilient device, said resilient device being under a stress whereby it is adapted to maintain, during operation of the pump, continuous Contact between each piston rod and the rocking device, hctweeneach piston rod and the cam mechanism acting thereon and between said member on to which the rocking ated'by liquid under pressure. comprising a number of pump chambers connected in series, a piston in each chamber adapted to reciprocate, piston rods carrying said pistons, rotating cam mechanism adapted to actuateeach piston rod to move the piston carried thereby through its power stroke and to permit each piston to perform its return stroke in a period shorter thanthat occupied by'the power stroke, a rocking device actuated by the piston rod of each piston during its power stroke to move another piston rod and the piston carried thereby through its return stroke, amember on which said rocking device is pivoted, a rotating cam impartingv a reciprocating motion to said memberandtherefore to the pivot of the'rocking device, and having its profile of such shape that the'rod of each piston is maintained during its return stroke substan tially in contact with the cam device by which it 'is caused to perform its power stroke, a resilient device forming a part of said member. on which the rocking device is [pivoted and situated intermediately of the .tween said member on to which the rocking device is pivoted, and the cam acting thereon, and means for adjusting the said resilient device with respect to the stress to which it is subjected.

In testimony whereofI have signed my namefto this specification.v

' W LLI M JOSEPH RUSDELL. 

